In the related art, some multiplexing devices (such as time division multiplexing devices) that collect and communicate the input and output signals of multiple devices may use optical fiber cables in order to increase the data transfer rate. For example, a technique for constructing a network in which multiple input and output devices (a master device, a slave device, or the like) are connected to each other by an optical fiber cable is disclosed (for example, PTL 1, or the like). In a communication system disclosed in PTL 1, data is transmitted by multiplex communication, and in a case where a communication abnormality occurs in the network due to a cause such as disconnection of the optical fiber cable, information relating to the occurred abnormality is transmitted, and a recovery process is performed.